I recently treaded into the dreaded territory of the Facebook API to try to create a viral app on top of AvantCard. I ran into a lot of snags that I'll share, and luckily found the solutions (which I will share as well).
The big thing I learned the hard way was that Facebook is requiring OAuth 2.0 authentication by September 1, 2011 and their Python-SDK does not support that.
So I went into facebook.py and tweaked the cookie-getter function to look for "fbsr_" vs "fbs" and then discovered they were just completely different and even doing that wouldn't fix the problem.
So I did just that, and it allowed me to successfully, get a user to the log-in screen, and generate the cookie, and get the cookie to get access to the Facebook access_token for that user. The only thing I need to do is throw in some JQuery to let the user not have to physically switch web-pages to do a Facebook login, and simply have a pop-up.
The other handy-dandy thing I fell upon was a pre-made function to handle FQL queries in Python really easily by just adding some code into the facebook.py file in the Python-SDK. Here's the site. Even though the site has you put the function inside facebook.py, I just modified it slightly to work in my controllers file for my Django/Python app.
Hopefully if anyone else out there is trying to get their Python app to work with Facebook's new OAuth 2.0 authentication system, you found this helpful.